Advanced method of heavy hydrocarbon removal and natural gas liquefaction using closed-loop refrigeration system

A natural gas liquefaction method comprising:

• (A) introducing a low-pressure natural gas stream into a natural gas liquefaction system, wherein the low-pressure natural gas stream comprises a pressure of less than 400 psig and a temperature between 50° F. and 100° F., and further wherein the natural gas liquefaction system comprises:
• a natural gas (NG)-to-liquefied natural gas (LNG) portion;
• and
• a closed-loop refrigeration portion comprising a closed-loop gaseous nitrogen expansion refrigeration system;
• wherein the NG-to-LNG portion and the closed-loop refrigeration portion are joined by a heat exchanger;
• (B) passing the low-pressure natural gas stream through the NG-to-LNG portion to provide a liquified natural gas stream and a vaporized natural gas liquid stream, wherein step (B) comprises:
• (i) increasing the pressure of the low-pressure natural gas stream via a first pressure booster device to provide a pressure-increased natural gas stream, wherein the pressure-increased natural gas stream comprises a pressure between 400 psig and 600 psig;
• (ii) treating the pressure-increased natural gas stream via a feed gas front treatment (FGFT) system to provide a treated pressure-increased natural gas stream;
• (iii) cooling the treated pressure-increased natural gas stream via a first pass of the heat exchanger to provide a cold partially-condensed natural gas stream, wherein the cold partially-condensed natural gas stream comprises a temperature between −120° F. and −80° F.;
• (iv) separating the cold partially-condensed natural gas stream via a cold gas separator into a vapor product stream and a liquid product stream;
• (v) warming the liquid product stream via a second pass of the heat exchanger to provide the vaporized natural gas liquid stream, wherein the liquid product stream is routed to the second pass of the heat exchanger by a level control valve;
• (vi) warming the vapor product stream via a third pass of the heat exchanger to provide a warmed vapor product stream;
• (vii) increasing the pressure of the warmed vapor product stream via a second pressure booster device to provide a compressed vapor stream, wherein the compressed vapor stream comprises a pressure between 800 psig and 1100 psig;
• (viii) cooling the compressed vapor stream via a cooling device to provide a de-superheated compressed vapor stream, wherein the de-superheated compressed vapor stream comprises a temperature between 80° F. and 120° F.;
• and
• (ix) cooling the de-superheated compressed vapor stream via a fourth pass of the heat exchanger to provide the liquefied natural gas stream, wherein the liquefied natural gas stream comprises a temperature between −250° F. and −265° F.;
• and
• (C) circulating a nitrogen refrigerant through the closed-loop gaseous nitrogen expansion refrigerant system to provide cooling to the NG-to-LNG portion.